Monte Carlo LT1 Build

[Adam]

Some decision points.

Exhaust system.
The Monte has headers and real dual exhaust (not to be confused with duel exhaust). The factory system had a single cat and dual Y-pipes. I would need to run a pair of cats (need to keep the emissions system of the Caprice intact). All options require purchasing new cats. If I was really looking to be cheap, I could reuse the existing cats, welding the cut pipe back together, but that is probably not advised as they do have 171K on them, plus all the idling time during police service.

Options:
- I could use LT1 manifolds and cats and adapt the cats to the existing exhaust system.
- I could use the headers and install some cats to the rear of the collectors.
- I could locate a B-body header/cat combination and hope it fits into the G-body.

Transmission:
- Shift kit or no. With the "cop chip" shifting calibration, it already shifts firmly and quickly.
- Torque converter upgrade or reuse. The one that's in it is turquoise and came with the junkyard trans.

Camshaft: <== fixed
- Minimal extra labor if I am doing this now. I plan on taking apart most of the components I need to remove to do this job anyway. Emissions compliance would play into this decision.
- 1.6:1 rockers. Doesn't require a cam swap, but would work if I did that too.

[Adam]

If I do use the headers in the Monte currently, I would also need to attach the A.I.R. injection system to the headers somehow as I need to retain the emissions system. Also O2 attachment to the collectors (includes extending the harnesses as well).

[Adam]

I should probably move the post-disassembly stuff into a separate thread.

[kevm14]

I've soaked most of the front suspension in PB Blaster, so that might help later. The exhaust will take a little work to get out, or I can just wait until the rear axle is removed. It is in good shape, though. It might be worth replacing the front flanges before reusing it as they are looking a bit rusty. The Roadmaster may need some exhaust soon, plus Amanda seems excited for it to sound like my Caprice used to (minus the addition of resonators and wagon tailpipes).

Yeah I'd keep the resonators. Also there may be a loss of low end torque. It will, however, sound very nice. Muscle wagon!

[kevm14]

Things I should probably do:
- Opti. Not free.
- Valve stem seals. Cheap. Can be done w/o pulling the heads. From looking into the exhaust ports, at least one seems to be leaking a little.
- Intake manifold gasket? Probably is fine, but the engine is out...

Opti is not a bad idea.

I would be surprised if the valve stem seals needed to be replaced. However, if you pull the valve covers to replace the gaskets, and you also decide to do a cam, you will need to replace the valve springs also, at which point you can do stem seals.

Resealing the intake would be part of the cam job and isn't a bad idea. It is a "problem area" on LT1s (relatively speaking).

[kevm14]

Exhaust system.
The Monte has headers and real dual exhaust (not to be confused with duel exhaust). The factory system had a single cat and dual Y-pipes. I would need to run a pair of cats (need to keep the emissions system of the Caprice intact). All options require purchasing new cats. If I was really looking to be cheap, I could reuse the existing cats, welding the cut pipe back together, but that is probably not advised as they do have 171K on them, plus all the idling time during police service.

Options:
- I could use LT1 manifolds and cats and adapt the cats to the existing exhaust system.
- I could use the headers and install some cats to the rear of the collectors.
- I could locate a B-body header/cat combination and hope it fits into the G-body.

You will probably be fine with a good quality high flow aftermarket cat, like a Walker (I think they make them). I don't think the cat will be too restrictive for your plans, but if you are replacing them, just go high flow.

If you use the headers, I'd consider wrapping them. Keeps heat out of the engine bay and the cats will work better.

Transmission:
- Shift kit or no. With the "cop chip" shifting calibration, it already shifts firmly and quickly.
- Torque converter upgrade or reuse. The one that's in it is turquoise and came with the junkyard trans.

The Trans-Go is the standard and is recommended generally. In your application, you can probably get away with increased power from stock, since the car is lighter and has ridiculous gears. The stock torque converter is also incredibly tight, but in your application, I don't think it will be a problem.

Camshaft: <== fixed
- Minimal extra labor if I am doing this now. I plan on taking apart most of the components I need to remove to do this job anyway. Emissions compliance would play into this decision.
- 1.6:1 rockers. Doesn't require a cam swap, but would work if I did that too.

I think there are quite a few good cam choices for the LT1. Browsing here, http://www.impalassforum.com/vBulletin/ ... p?t=227230, and jogging my memory, I'd recommend looking into:
- GM P/N 12370846 Hydraulic roller design I:222 E:230 I:509" E:528" 112. There is also a milder '845, and a hotter '847.
- Comp Cams 305 220/230 .544/.544 114lsa) w/ 1.6RR's. The 304 will make 300 rwhp with supporting airflow mods and push a B-body through the 1/4 in about 13.7 @ 100.
- Crane 227 cam 210/224 .511/.553 112lsa) w/1.6RR's. Good for a heavy B-body, maybe not quite enough for a lighter application with gears.

More cam guidance here: http://www.impalassforum.com/vBulletin/ ... p?t=248812

Some things from there:
- Stock 1996 B-Body Camshaft Specs: 191/196 0.418/0.430 lift 111 LSA
- Can look at the Comp XFI or XE series. More aggressive ramps and they require beehive valve springs.

Probably want to replace the lifters also. Fun fact:

Yes the LS7 lifters will work in an LTx motor, they are one of the only interchangeable components between LSx and LTx motors. If you go to your local GM dealer to order lifters for your LT1, they will give you LS7's because they are the newly revised replacements.

I would bet that around the 220° intake duration range you may want a converter (nothing crazy). Then again, it is a light car with very steep gears.

[kevm14]

I should probably move the post-disassembly stuff into a separate thread.

Create a Monte build thread and I'll move the relevant posts into it.

[Adam]

I'm going to put an LT1 and 4L60E from a '94 9C1 Caprice in an '85 Monte Carlo SS.

[kevm14]

You will need upgraded injectors with the cam, such as 30 lb/hr Ford SVO injectors (popular). You will also want an upgraded fuel pump, such as the Walbro 255 lph. I will do a little digging and see about more confident recommendations (these may still be good choices).

You will also want to run the right gauge of wire for that pump. Not sure what that is but perhaps 10 ga? 12 ga?

[kevm14]

More thoughts on the cam: about as far as you can go on the stock heads (airflow reasons) may match up well to your drivability, emissions and fuel economy goals. I don't remember off hand how much lift you can run without machining down the valve guides. More research.